Technology is here to give us shortcuts.

For example, voice mails should not consist of "Hi, this is blah, call me back".  They got that much from the Missed Call list on their phone.  You just made someone waste a minute of their life, and press buttons they didn't need to press.  If this happens a number of times in a day it adds up to a large inconvenience.

Choose the right medium for the message

If you want someone to read something short, very soon, and don't care about a confirmation or affirmation, send a text message.  Text messages should be short.  There are multiple reasons they should be short.  The first reason is, it is inconvenient for you to type a long message.  The second reason, they are non-persistent - they are not archived anywhere for permanence to be referenced.  If you type out a long set of directions for example, it can't be saved or printed easily, and probably not referred back to.

Good examples: be there in 15, are we still on?, what time is the thing? Happy Birthday, I miss you, etc.

If you have data in a message, email is best.  Email is archived, saved, search able, forward-able, printable, it's great.  You should never have to send an email with just the word "ok" .

Example, you start out texting about an event, "will you be there, tell me about the place?"  This should turn into an email at this point if possible.  Then the email can have dates, times, pictures, and even be forwarded and printed! Great!

Voicemail should ONLY be used when for some strange reason you have a message that can't wait for email, and you want to convey more emotion than a text or email.  Voicemail is horrible.  It takes longer to check that email or texts, it is difficult or impossible to forward, you can't print it, search it, or save it for a long time. 

You can use voicemail if you want to tell someone something very personal that isn't safe for email, don't give DETAILS on voicemail, but you can ask them in the right tone to call you back because it's important.  This won't leave a lasting trail, so it can be useful when you don't WANT it forwarded or saved forever.

Treat Instant Messenger like a text message

You do NOT have to respond right away.  You don't have to respond at all.  Very short messages, nothing with significant data.  They can't be searched, indexed, archived, printed, forwarded easily.  A little better than a text message, but not much.  If your signed in to a computer that you hardly use, then you might not even see the message for a few days.  This is normal, happens all the time, and users know of this limitation and expect it.  Nothing time sensitive can happen over instant messenger.

Response times

Response times vary from medium to medium - and situations have an effect on an acceptable time. 

Text Message: IF the message needs a response, a few hours to 12 hours is normal.  A day is pretty long, longer should only be because your phone is dead, lost, no service.

Instant Message: IF the message needs a response, 1 hour to 3 days is completely normal. (since you are using the computer for work, and might leave it for a while, this should be expected)

Email: 1 day is nice, 3 days is the max normal response time.  If you take longer it's because of a situation like vacation, long weekend, no service, looking something up, etc

Voicemail: Same Day.  How annoying.. Just do it.. better yet, text them back.  Then it's out of your court.